Let’s start with a very obvious statement: Scales are only useful if they accurately measure weight. If we can agree on that point, then we can agree that calibrating a scale is important. Calibrating a scale proves it is weighing accurately. But the question remains… how to calibrate a digital scale? Let’s review how to calibrate a digital scale and take a look at some common calibration techniques and tips.
Why do I need to calibrate my scale?
You might be wondering why you need to calibrate a scale. It is true scales are calibrated by the manufacturer before they are shipped to you or the store you bought your scale from. But scales become less calibrated over time. The level of inaccuracy and the time it takes to become less accurate usually depend on the quality of the scale. So if you have a high quality digital scale, you probably don’t need to worry about calibrating it as often. Whereas, if you have a cheap and low quality digital scale you might want to make sure it’s calibrated more often.
Some kitchen and food scales don’t have the ability to be calibrated. These scales are often lower price points and can easily be replaced if they are no longer accurately measuring.
Another consideration is what you use your scale for. The more important accurate measuring is for you, the more important it is to make sure your scale is calibrated. If precision is important for your use of scales, consider calibrating a regular activity. Some examples of scale usage that would warrant more frequent calibration include:
- Precision-based cooking/baking
- Espresso ratios
- Reloading scales (ammo)
- Supplement weighing for body building
- Fine jewelry weighing
- Pharmaceutical weighing
- Cannabis weighing
Finally, the frequency of using your scale can also contribute to the calibration falling off. If your scale is used multiple times per day it will likely need to be recalibrated more often than a scale used a few times per week.
Next, let’s take a look at what you need to calibrate before getting into how to calibrate a digital scale.
Calibrating Digital Scale Essentials
To properly calibrate a digital scale you need 3 things:
- A digital scale
- A calibration weight
- A flat surface
Digital Scale
It is obvious you need a digital scale in order to calibrate a digital scale. But it’s also important to note that all digital scales are different. Some digital scales can’t even be calibrated. You should always consult your scale’s user manual to know the specifics of the scale and how to calibrate it specifically. Because it’s not possible to cover every scale’s specifics, please note this post is covering how to calibrate a digital scale generally. Some of these points might not be relevant or accurate for your specific scale.
A tip: if you don’t have the user manual for your scale, most of the time you can find a digital version of user manuals just by Googling your scales make and model. If you are looking for a new scale, check out our list of the best kitchen scales.
Calibration Weight
What is a calibration weight? Calibration weights are standardized weights that are certified by international, national, or industrial organizations. Each calibration weight has a precise mass that makes it suitable for calibrating scales to ensure subsequent weight measurements are accurate.
Some scales come with their own calibration weights but many do not. You can easily find calibration weights online or in stores, but here are our 2 recommendations:
Flat Surface
When calibrating a digital scale, it is imperative you use a flat surface. This can greatly impact the calibration. You should also be aware of other factors like strong drafts or abnormal temperatures as these can also impact the calibration process.
How to calibrate a digital scale
1. Check to see if your scale needs to be calibrated
Before calibrating, test your scale with a calibration weight by putting the calibration weight on the scale and checking if the scale reads the weight of the calibration weight correctly. If the scale properly measures the calibration weight, you can be sure your scale is good to use with confidence and do not need to calibrate.
2. Consult your scale’s manual for any specific considerations for calibration
As we mentioned, scales can have their own calibration method although most follow the same general steps. Before getting started, make sure you read your scale’s manual to understand any specific steps or considerations that might not be covered here. The most important thing to identify is where the calibration button is on your scale.
3. Clean your scale
You don’t want any leftover debris or dried liquid impacting your calibration. It’s also a good chance to give your scale a wipe over, making sure it is completely free of any crumbs or other items.
4. Gather your supplies and set scale on a flat surface
Make sure you have your scale on a flat and stable surface and get your calibration weight. Note that some scales are configured to use their specific included calibration weight and won’t be able to use a different weight. If you have misplaced your scale’s specific calibration weight you can get a new calibration weight as long as it weights the EXACT same as the one that was included with your scale.
5. Find your scale’s calibration button to begin calibration mode
Most scales that can be calibrated will either have a specific button for calibration (“C” or “CAL”) or by pressing the ‘Mode’ button (sometimes pressing and holding down). Refer back to step 2 and your scale’s instruction manual if needed. Press the button(s) to get your scale into calibration mode.
6. Use the calibration weight to complete calibration
Make sure you place your calibration weight at the center of the digital scale and not at the edge, to ensure proper accuracy. Make sure there is no movement to the weight during the calibration process. For some scales, you will enter the calibration weight on the screen and lock in the calibration button. If the weight came included with the scale, the weight is likely pre-programmed in the digital scale. Let the scale take in the measurement.
If needed, press the calibration button to end the calibration mode and the scale will display the following words, “End”, “Cal”, or “0”. Scales with pre-programmed weights may also display “Pass” when calibration is completed. The scale will most likely reset automatically , but if it does not, you should switch off the scale for about 2-3 minutes before using.
7. Use your calibrated scale with confidence
How to calibrate a digital scale without a weight?
There is a method to calibrate a digital scale without a calibration. It is not as accurate but if you are not concerned about extreme precision and badly need to calibrate it might be worth it to use this method.
This method is based on the following estimates, which are usually pretty accurate:
It should be noted the weights of coins in circulation are not exact. For the most part, coins should be very close to their original weights but if a coin has been in circulation for years it has eroded and will not weight this exact amount.
Using either nickels or pennies you can “recreate” a calibration weight. So using either 10 nickels (~50g) or 20 pennies (~50g), you can see if your scale needs to be calibrated. If it reads 50g after placing the coins on it, it is close to calibrated (remember, this method is not exact).
If the measurement is off, you use the same steps as above but instead of a calibration weight you mimic the weight using nickels or pennies. So if the calibration weight is supposed to be 100g, you can use either 40 pennies or 20 nickels.
If you have something in your house that has an exact weight on it that matches the calibration weight, you could also use that. Even without a calibration weight, you now know how to calibrate a digital scale!
Conclusion
Now that you know how to calibrate a digital scale you can continue to weigh with confidence. Remember these key points:
- Not every scale can be calibrated, in many cases normal kitchen or food scales can more easily be replaced than calibrated
- How you use your scale (e.g. if precision is important) and the frequency of use both contribute to how often you should calibrate your scale
- You can always check to see if your scale needs to be calibrated before going through the calibration process
If you want more scientific information behind scale calibration, check out this article from AML Instruments.